Tali Sharot

The concept of unrealistic optimism can be traced back to Descartes as well as the German polymath Gottfried Wilhelm Leibniz, who notably held that we live in "the best of all possible worlds." Voltaire famously ridiculed Leibniz’s theory in his Candide, wherein Dr. Pangloss contemplates human suffering and misfortune only to assert that all is for the best!

The social psychologist Neil Weinstein is credited for first demonstrating the phenomenon empirically.

I would like to clarify a common misunderstanding that comes up if people do not read our original Nature Neuroscience paper (which I urge you to do if you really want to understand the specifics of this study). Each participant in the study was asked to estimate their likelihood of experiencing 80 different negative events. While it is certainly possible that, for example, a participant (or even most participants) is less likely to suffer a specific illness than the average, this study is not about people’s perceptions of their vulnerability per se (and in that sense it is very different from past studies of the optimism bias). Rather, we study how people update these perceptions. We find that people alter their beliefs more when they receive information that is better than expected, rather than worse. This finding cannot be explained by whether you are in fact more or less likely to suffer these events or by whether the information I give you is accurate for you (because if you believe it was not accurate you should not update your beliefs at all, not even when you get good information). We have since replicated these findings in almost 1,000 individuals across the world in at least 10 independent studies using different designs of our task.

It is important to note that the colored clusters in the brain images do not represent greater brain activity. Rather, the colored regions show you areas in the brain where the amount of activity on each of the 80 trials is correlated with how good or bad information is relative to your expectations. In other words, these are regions where we think neuronal activity represents accurate computations that are needed to alter beliefs. You can have lots of activity in your brain when you get bad news, but that activity may be noisy, rather than a clear signal that relates to the information you were given.

Another misconception is that these findings suggest that the inferior frontal gyrus (IFG) is solely responsible for optimism. This is not the case. First, we have shown that the IFG works in concert with many other regions. Second, optimism is a multifaceted concept. Here, we are only looking at one function that is related to optimism (how you learn about probabilities). There are other important functions that give rise to optimism that I did not have time to cover in 18 minutes (like imagination and memory).